This invention relates to a split ring clutch, and more particularly to such a clutch which is suitable for intermittent motion or indexing of a rotatable shaft or disk.
A number of clutches for intermittent application have been developed in the past. A conventional clutch mechanism, for example, incorporates a clutch plate which is forced against a rotatable member for imparting angular movement to the clutch plate. Such a mechanism is normally not self engaging, is made up of a large number of parts, and requires a relatively large operating force, and a large motion to move between engaged and disengaged positions. It also requires a friction disk which is subject to wear, and has a relatively high inertia for any given torque rating.
An alternative clutch arrangement incorporates sprag or needle bearings. Such a clutch is capable of rotation in one direction, but no disengagement is possible in the reverse direction of rotation. It typically requires a thick, high inertia shell, and in the event of a torque overload, a catastrophic failure results. The needle rollers and sprag are highly stressed, and the clutch is not adjustable with respect to a torque limit.
A spiral spring clutch has been used for applications requiring a low torque rating. Such a clutch has relatively large drag forces, and operates in only one direction. Also, it has a high rotational flex at high torque levels, and the spring ends are subject to breakage. A chain and lever clutch design has also been proposed, which is characterized by high flexing, and relatively low torque. It does not have precision engagement, and operates in a single direction of rotation.